A seismic prospecting assembly comprises detectors disposed in a predetermined configuration on the gournd and connected by cables or radio to a central recording station. The assembly is of course completed by sources of artificial seismic shocks.
On land the detectors are geophones. At sea they are hydrophones. These remains the intermediate case of the shoreline or very marshy zones (shallow water) where geophones and hydrophones must be used jointly in the same apparatus. It is moreover desirable to provide a geophone and hydrophone at those locations for the detector which are sometimes dry and sometimes submerged (for example, by the tides). Land operators must therefore modify the connection of each particular "brace" (elementary line of detectors) every time to change over from the geophonic to the hydrophonic mode, and vice versa.
The result is either a substantial lengthening of the time of collecting seismic data, or the need to make do with incomplete information if during measurement the geophones were submerged, or the hydrophones were dry. Hitherto no satisfactory solution to this problem has been suggested.
It is an object of the invention to provide a detector adapted to perform the functions of a geophone and a hydrophone interchangeably and reliably.